249 lines
11 KiB
Rust
249 lines
11 KiB
Rust
use crate::mbe::macro_parser;
|
|
use crate::mbe::{Delimited, KleeneOp, KleeneToken, SequenceRepetition, TokenTree};
|
|
|
|
use rustc_ast_pretty::pprust;
|
|
use rustc_session::parse::ParseSess;
|
|
use rustc_span::symbol::kw;
|
|
use syntax::ast;
|
|
use syntax::token::{self, Token};
|
|
use syntax::tokenstream;
|
|
|
|
use rustc_span::Span;
|
|
|
|
use rustc_data_structures::sync::Lrc;
|
|
|
|
/// Takes a `tokenstream::TokenStream` and returns a `Vec<self::TokenTree>`. Specifically, this
|
|
/// takes a generic `TokenStream`, such as is used in the rest of the compiler, and returns a
|
|
/// collection of `TokenTree` for use in parsing a macro.
|
|
///
|
|
/// # Parameters
|
|
///
|
|
/// - `input`: a token stream to read from, the contents of which we are parsing.
|
|
/// - `expect_matchers`: `parse` can be used to parse either the "patterns" or the "body" of a
|
|
/// macro. Both take roughly the same form _except_ that in a pattern, metavars are declared with
|
|
/// their "matcher" type. For example `$var:expr` or `$id:ident`. In this example, `expr` and
|
|
/// `ident` are "matchers". They are not present in the body of a macro rule -- just in the
|
|
/// pattern, so we pass a parameter to indicate whether to expect them or not.
|
|
/// - `sess`: the parsing session. Any errors will be emitted to this session.
|
|
/// - `features`, `attrs`: language feature flags and attributes so that we know whether to use
|
|
/// unstable features or not.
|
|
/// - `edition`: which edition are we in.
|
|
/// - `macro_node_id`: the NodeId of the macro we are parsing.
|
|
///
|
|
/// # Returns
|
|
///
|
|
/// A collection of `self::TokenTree`. There may also be some errors emitted to `sess`.
|
|
pub(super) fn parse(
|
|
input: tokenstream::TokenStream,
|
|
expect_matchers: bool,
|
|
sess: &ParseSess,
|
|
) -> Vec<TokenTree> {
|
|
// Will contain the final collection of `self::TokenTree`
|
|
let mut result = Vec::new();
|
|
|
|
// For each token tree in `input`, parse the token into a `self::TokenTree`, consuming
|
|
// additional trees if need be.
|
|
let mut trees = input.trees();
|
|
while let Some(tree) = trees.next() {
|
|
// Given the parsed tree, if there is a metavar and we are expecting matchers, actually
|
|
// parse out the matcher (i.e., in `$id:ident` this would parse the `:` and `ident`).
|
|
let tree = parse_tree(tree, &mut trees, expect_matchers, sess);
|
|
match tree {
|
|
TokenTree::MetaVar(start_sp, ident) if expect_matchers => {
|
|
let span = match trees.next() {
|
|
Some(tokenstream::TokenTree::Token(Token { kind: token::Colon, span })) => {
|
|
match trees.next() {
|
|
Some(tokenstream::TokenTree::Token(token)) => match token.ident() {
|
|
Some((kind, _)) => {
|
|
let span = token.span.with_lo(start_sp.lo());
|
|
result.push(TokenTree::MetaVarDecl(span, ident, kind));
|
|
continue;
|
|
}
|
|
_ => token.span,
|
|
},
|
|
tree => tree.as_ref().map(tokenstream::TokenTree::span).unwrap_or(span),
|
|
}
|
|
}
|
|
tree => tree.as_ref().map(tokenstream::TokenTree::span).unwrap_or(start_sp),
|
|
};
|
|
sess.missing_fragment_specifiers.borrow_mut().insert(span);
|
|
result.push(TokenTree::MetaVarDecl(span, ident, ast::Ident::invalid()));
|
|
}
|
|
|
|
// Not a metavar or no matchers allowed, so just return the tree
|
|
_ => result.push(tree),
|
|
}
|
|
}
|
|
result
|
|
}
|
|
|
|
/// Takes a `tokenstream::TokenTree` and returns a `self::TokenTree`. Specifically, this takes a
|
|
/// generic `TokenTree`, such as is used in the rest of the compiler, and returns a `TokenTree`
|
|
/// for use in parsing a macro.
|
|
///
|
|
/// Converting the given tree may involve reading more tokens.
|
|
///
|
|
/// # Parameters
|
|
///
|
|
/// - `tree`: the tree we wish to convert.
|
|
/// - `trees`: an iterator over trees. We may need to read more tokens from it in order to finish
|
|
/// converting `tree`
|
|
/// - `expect_matchers`: same as for `parse` (see above).
|
|
/// - `sess`: the parsing session. Any errors will be emitted to this session.
|
|
/// - `features`, `attrs`: language feature flags and attributes so that we know whether to use
|
|
/// unstable features or not.
|
|
fn parse_tree(
|
|
tree: tokenstream::TokenTree,
|
|
trees: &mut impl Iterator<Item = tokenstream::TokenTree>,
|
|
expect_matchers: bool,
|
|
sess: &ParseSess,
|
|
) -> TokenTree {
|
|
// Depending on what `tree` is, we could be parsing different parts of a macro
|
|
match tree {
|
|
// `tree` is a `$` token. Look at the next token in `trees`
|
|
tokenstream::TokenTree::Token(Token { kind: token::Dollar, span }) => match trees.next() {
|
|
// `tree` is followed by a delimited set of token trees. This indicates the beginning
|
|
// of a repetition sequence in the macro (e.g. `$(pat)*`).
|
|
Some(tokenstream::TokenTree::Delimited(span, delim, tts)) => {
|
|
// Must have `(` not `{` or `[`
|
|
if delim != token::Paren {
|
|
let tok = pprust::token_kind_to_string(&token::OpenDelim(delim));
|
|
let msg = format!("expected `(`, found `{}`", tok);
|
|
sess.span_diagnostic.span_err(span.entire(), &msg);
|
|
}
|
|
// Parse the contents of the sequence itself
|
|
let sequence = parse(tts.into(), expect_matchers, sess);
|
|
// Get the Kleene operator and optional separator
|
|
let (separator, kleene) = parse_sep_and_kleene_op(trees, span.entire(), sess);
|
|
// Count the number of captured "names" (i.e., named metavars)
|
|
let name_captures = macro_parser::count_names(&sequence);
|
|
TokenTree::Sequence(
|
|
span,
|
|
Lrc::new(SequenceRepetition {
|
|
tts: sequence,
|
|
separator,
|
|
kleene,
|
|
num_captures: name_captures,
|
|
}),
|
|
)
|
|
}
|
|
|
|
// `tree` is followed by an `ident`. This could be `$meta_var` or the `$crate` special
|
|
// metavariable that names the crate of the invocation.
|
|
Some(tokenstream::TokenTree::Token(token)) if token.is_ident() => {
|
|
let (ident, is_raw) = token.ident().unwrap();
|
|
let span = ident.span.with_lo(span.lo());
|
|
if ident.name == kw::Crate && !is_raw {
|
|
TokenTree::token(token::Ident(kw::DollarCrate, is_raw), span)
|
|
} else {
|
|
TokenTree::MetaVar(span, ident)
|
|
}
|
|
}
|
|
|
|
// `tree` is followed by a random token. This is an error.
|
|
Some(tokenstream::TokenTree::Token(token)) => {
|
|
let msg =
|
|
format!("expected identifier, found `{}`", pprust::token_to_string(&token),);
|
|
sess.span_diagnostic.span_err(token.span, &msg);
|
|
TokenTree::MetaVar(token.span, ast::Ident::invalid())
|
|
}
|
|
|
|
// There are no more tokens. Just return the `$` we already have.
|
|
None => TokenTree::token(token::Dollar, span),
|
|
},
|
|
|
|
// `tree` is an arbitrary token. Keep it.
|
|
tokenstream::TokenTree::Token(token) => TokenTree::Token(token),
|
|
|
|
// `tree` is the beginning of a delimited set of tokens (e.g., `(` or `{`). We need to
|
|
// descend into the delimited set and further parse it.
|
|
tokenstream::TokenTree::Delimited(span, delim, tts) => TokenTree::Delimited(
|
|
span,
|
|
Lrc::new(Delimited { delim, tts: parse(tts.into(), expect_matchers, sess) }),
|
|
),
|
|
}
|
|
}
|
|
|
|
/// Takes a token and returns `Some(KleeneOp)` if the token is `+` `*` or `?`. Otherwise, return
|
|
/// `None`.
|
|
fn kleene_op(token: &Token) -> Option<KleeneOp> {
|
|
match token.kind {
|
|
token::BinOp(token::Star) => Some(KleeneOp::ZeroOrMore),
|
|
token::BinOp(token::Plus) => Some(KleeneOp::OneOrMore),
|
|
token::Question => Some(KleeneOp::ZeroOrOne),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
/// Parse the next token tree of the input looking for a KleeneOp. Returns
|
|
///
|
|
/// - Ok(Ok((op, span))) if the next token tree is a KleeneOp
|
|
/// - Ok(Err(tok, span)) if the next token tree is a token but not a KleeneOp
|
|
/// - Err(span) if the next token tree is not a token
|
|
fn parse_kleene_op(
|
|
input: &mut impl Iterator<Item = tokenstream::TokenTree>,
|
|
span: Span,
|
|
) -> Result<Result<(KleeneOp, Span), Token>, Span> {
|
|
match input.next() {
|
|
Some(tokenstream::TokenTree::Token(token)) => match kleene_op(&token) {
|
|
Some(op) => Ok(Ok((op, token.span))),
|
|
None => Ok(Err(token)),
|
|
},
|
|
tree => Err(tree.as_ref().map(tokenstream::TokenTree::span).unwrap_or(span)),
|
|
}
|
|
}
|
|
|
|
/// Attempt to parse a single Kleene star, possibly with a separator.
|
|
///
|
|
/// For example, in a pattern such as `$(a),*`, `a` is the pattern to be repeated, `,` is the
|
|
/// separator, and `*` is the Kleene operator. This function is specifically concerned with parsing
|
|
/// the last two tokens of such a pattern: namely, the optional separator and the Kleene operator
|
|
/// itself. Note that here we are parsing the _macro_ itself, rather than trying to match some
|
|
/// stream of tokens in an invocation of a macro.
|
|
///
|
|
/// This function will take some input iterator `input` corresponding to `span` and a parsing
|
|
/// session `sess`. If the next one (or possibly two) tokens in `input` correspond to a Kleene
|
|
/// operator and separator, then a tuple with `(separator, KleeneOp)` is returned. Otherwise, an
|
|
/// error with the appropriate span is emitted to `sess` and a dummy value is returned.
|
|
fn parse_sep_and_kleene_op(
|
|
input: &mut impl Iterator<Item = tokenstream::TokenTree>,
|
|
span: Span,
|
|
sess: &ParseSess,
|
|
) -> (Option<Token>, KleeneToken) {
|
|
// We basically look at two token trees here, denoted as #1 and #2 below
|
|
let span = match parse_kleene_op(input, span) {
|
|
// #1 is a `?`, `+`, or `*` KleeneOp
|
|
Ok(Ok((op, span))) => return (None, KleeneToken::new(op, span)),
|
|
|
|
// #1 is a separator followed by #2, a KleeneOp
|
|
Ok(Err(token)) => match parse_kleene_op(input, token.span) {
|
|
// #2 is the `?` Kleene op, which does not take a separator (error)
|
|
Ok(Ok((KleeneOp::ZeroOrOne, span))) => {
|
|
// Error!
|
|
sess.span_diagnostic.span_err(
|
|
token.span,
|
|
"the `?` macro repetition operator does not take a separator",
|
|
);
|
|
|
|
// Return a dummy
|
|
return (None, KleeneToken::new(KleeneOp::ZeroOrMore, span));
|
|
}
|
|
|
|
// #2 is a KleeneOp :D
|
|
Ok(Ok((op, span))) => return (Some(token), KleeneToken::new(op, span)),
|
|
|
|
// #2 is a random token or not a token at all :(
|
|
Ok(Err(Token { span, .. })) | Err(span) => span,
|
|
},
|
|
|
|
// #1 is not a token
|
|
Err(span) => span,
|
|
};
|
|
|
|
// If we ever get to this point, we have experienced an "unexpected token" error
|
|
sess.span_diagnostic.span_err(span, "expected one of: `*`, `+`, or `?`");
|
|
|
|
// Return a dummy
|
|
(None, KleeneToken::new(KleeneOp::ZeroOrMore, span))
|
|
}
|